The preparation of cyclododecene by the partial hydrogenation of 1,5,9-cyclododecatriene using ruthenium ligand complex catalysts is disclosed in U.S. Pat. Nos. 3,925,494 and 3,804,914 to Fahey. The reaction is also disclosed in J. Ore. Chem., Vol. 38, No. 1, 1973, pages 80-86, by Darryl R. Fahey.
In the '914 patent the reaction is carried out in various solvents.
It is desirable to carry out the process in a solvent because it is easier to control the catalyst concentration in that the catalyst is not soluble enough in 1,5,9-cyclododecatriene at room temperature to give efficient result, and heating a mixture of catalyst and 1,5,9-cyclododecatriene to increase the solubility of the catalyst also increases the amount of by-product formed. Furthermore, the hydrogenation of 1,5,9-cyclododecatriene is an exothermic reaction, and it is difficult to control the temperature of the reaction in the absence of a solvent. The presence of the solvent acts as a "heat sink" for the reaction. Upon completion of the reaction the product, cyclododecene is separated from the reaction mixture.
An object of the present invention is to provide a process from the production of cyclododecene from 1,5,9-cyclododecatriene in which it is easy to control catalyst concentration, easy to control the exotherm, and easy to separate the product from the reaction mixture. In addition the process is readily employed in a continuous manner, by recycling the portion of the reaction mixture remaining after removal of cyclododecene.